Steering systems



March 11, 1958 R. w. KETCHLEDGE 2,826,380

STEERING SYSTEMS Filed Dec. 28, 1944 mus l F/a/ om .9 RELA Tlv: F/G. 2

@c TARGET aum/vc 6H 6T T/we l No T asn-cron M'FeRE/vru Ton R4 TE orCHA/vae or /0 @LAT/VE TARGET sun/Nc co/vTRoL AcTuAL l5 /4 TARGET COURSEI3 arkoscoPE l *M25-'253515665 caNTnaL FIG. 3

44a 455 49 L 3Q-fr. /7 l l, ub 48- 3a q /45a l 43 47 /NVENTOR' I R.WKE'CHLEDGE A TTORNEY United States Pate-.ntl O F rsrnnmNG 'SYSTEMSRaymond W. Ketchledge, Jamaica, N. .Ya assignor to Bell TelephoneLaboratories, Incorporated, New York, N. Y., a corporation ofNew YorkApplicationnecember is, 1944, serial No. 510,180 L14 claims. (einzu-Jil)the for-m vcsf-.a pilotless aircraft, which iis lpar-ticularlysuittable,for use `against objects,such as .ships or ipower lplants,

the temperature of which is substantially different :from that of thesurrounding area;

A moving body, such as.=an aerial bomb, at any initial position relativeto a target, which may be stationary or tinovinfg, :may :follow 'anyjonefof :a :number Vof courses Ain 'ftraveling ftlie target For example, :in:the `case `iota moving target, the body `or bomb in its ight might becontrolled so that it was headed continuously toward the target, wherebyit would follow a generally curvilinear whom-ing course Also; for thiscase, the :bomb would meet the target if it werersteered along a'collision course,

i. e., a straight line at such angle to the path followed by the targetthat at some fpjint the positions of the bomb and target would coincide.

-For .the lcase where the bom-b follows a homing course, it- 1nrust-k besteered 2in 'accordance with therelaftive Ibearing QWthetargetMi-threspecttto'the bomb. .For the oase where the bomb is to follow acollision course,- :it must he steered in accordance withjthe truetarget bearing, i. e.,

and `-1itstl-vi-tig'-fcircuit f-for converting `energy emanating2,826,380 Patented Mar. 11, 1958 steering systems of the type adapted to`guide a body to a target l'in accordance 'with .information as to theposition or position and course ftlie target 'derived 'from wave energy"emanating from Vthe target :and detected at the 'body- Moiispecijcally,objects of invntion'are to:

Realize guidance of a body, 'by v'a steering Ysystem df the type abovenoted, along a collision course; Y

Inc'rease'the `steering accuracyof 'such Aa system; l

Enable attainment of desired control characteristics, Spcclly relativelyhigh stiffness of control, for such a system,

Reduce the `stringency of design recpiireinents for wave 'energyii'sponsive steering systems, particulaly such sys- 'tems `inte'i'lded:to be responsive to 'nergyenianating from a distant sour" Obtainstability of control in wave Ienergyresponsive nJot'e emliodirnnt ofinvention, a steering system for an arialbonb, which 'may be inthe formfrom a target in the field noted and .received by the 'de- "teemr sanscontrai signal rer causing operation if the "animar, A dated V"to 'scana :prescribed held, and a highly :sensitive actua-ier "ne,ilreiicn-erftliefste'ering member, :to .guide the bomb he target;`throne form., the detector 'comprises ceptive to infra-'redradiatifomwhich Vis lfossil- "b'olnmeter associated with ithe vmirror to Ireceiveinfra-.red

its bearing relative to a reference direction such as true north. Aswill be pointed out in some detail hereinafter,

the steeringtunction' for collision coarse steering necessithat lforBight :over a homing course. Further, l'collision course steering, Easwill -be 'demo'nstrate'd hereinafter, `has `inherent advantages fromt`h`e` standpoint of steering "coritrol and 'of bfnib maneuver-abilityin =the vicinity of `the target. On the other hand .it-may have adisadvantage at large distances from the target from the standpoint ofaccuracy of steering information required, due to the small value, atsuch distances, 1for the rate of change of "el't'e 'target' bearingltiln involved Vili' the steering 'Homing cos' steering, onthe other'hand, entails Iless 'stringent requirements upon bearing informationYnecessay to ffect 'steering at `great distances betweenlbomband itargetHowever, such 'steering may have the `disadvant-a'ge, particularly inthe `case ofbombsof substantial fs'iz'e, "in the vicinity 'ofthe target,"of -resticted 'accuacy'fdne to 'liiiiitezi` nianeuverabiiity lof the'bomb.

@ne "general -obeet l-of this' Llinvention :is to improveradiatienreectedr'fremztlie'niirror. n n

lvnjaecerdance jwith `one feature -o'f this invention, 'the resolving`tiir'otiit :is constructed Vand arranged ftoiprovide .a signalproportional to fthe .relative target beating, which .signal is .applied:to thecnntrel `1-Iirc11it-ifforftheactuator for the steering member insuch manner that, inthefabsence Aof other controls, the bomb is steeredalong a homing course. l, -In accordance withnnother feature of thisinvention, 'the resolving circuit is constructed and arranged to providealso a signal proportional to the rate of change of .relative 'targetbearing and `meansa-re fpriovirled for producinga third .sig-nalproportional to .rate-of change of v.bomb heading. The :two signals.noted are combined fand applied to the `control circuit .for thelactuator for the steering .member .in such manner that, in the abs/enceof other controls, the bomb is =steered along .the collision course. Y

'In -ccordance with affurther .feature o'f this invention,

v'the hoarding course andlcollision course*,signalsE are appliedsimultaneously to 'the control circliit noted in such relation that whenthe bomb is at a relatively great distance from the target it is steeredsubstantially along a homing .course whereas atrelatively .smalldistances from .the .target it ,is .steered substantially along Athecollision course.

VIn accordance with still another featu-reof invention, meansa'pro'vide'd 'for reversing the sense df the ra'te f change of headingsignal, as "applied 'to the control circit aforenotd, 'whenno tar-gefjenelfgy is received by 'the detector, whereby, if r condition, thesignal noted exerts a stabilizing .eiect upon the steering control.

'Th'efinvention Vand the above-noted 'and other l'features Fig. 2 is adiagram, in functional block form, of a steering system constructed inaccordance with this invention; and

Fig. 3 is a circuit diagram of a steering system illustrative of oneembodiment of this invention.

Referring now to the drawing, in Fig. l, a bomb andv target areindicated at arbitrary positions B and T respectively, and with theconnecting or base line BT therebetween at an arbitrary angle to truenorth. Assume that the target is moving in the direction of the line TXand that the bomb is moving in a direction generally toward this line.For given initial positions of the bomb and target and given velocities,and assuming that the bomb is steered toward the target, there existssome point at which the bomb and target will meet. It will be apparentthat the bomb may be directed or steered along a number of dilferentpaths to collide with the target. For example, if it follows a trueVcollision course it will travel along the straight line BC` and arriveat the point C at the same time as the target. Also, for example, it mayfollow a generally curvilinear or homing course and meet the target at apoint on the line TX.

The actual course, D, at any instant may be as indicated by the arrow sodesignated inpFig. l. The heading, 0H, of the bomb at any instant maynot coincide with the actual course, due to, for example, wind and otherfactors causing the bomb to turn, and may be as indicated by the arrowdesignated Heading in Fig. 1, to produce a relative target bearing 0T.

If the bomb follows a true collision course, at some time subsequent tothat corresponding to the positions B and T, the bomb and target will beat the positions indicated by B' and T' in Fig. l. It will be seen thata true collision course is followed, if the true bearing, (6H-HT), ofthe target remains constant. Thus, to realize collision course travel ofthe bomb, the steering can be accomplished in terms of the true Vtargetbearing, that is, by effecting steering in accordance with the timederivative of the true target bearing. Mathematically, the steeringfunction for collision course steering may be expressed, then, as

d adt where FH is the steering function and 0T is as dened above. Thisfunction may be considered as a measure of the steering correctionrequisite to return the bomb to a homing course if it deviates from sucha course.

Certain characteristics ofthe steering functions and of the termsinvolved therein must be considered in the design of any particularsteering system. Two factors of particular moment in the evaluation ofthe performance of a steering system are the stiffness of control thatmay be realized and the stability of the system. Stiffness `of controlmay be defined as the ratio of the steering effect, expressed, forexample, in terms of amplitude of rudder deflection, to the off courseangle of the body, e. g., bomb, being steered. Stability may be dened asfreedom from erratic steering behavior such as large amplitude,self-sustained, uoscillations Vof thefbody under steering control, aboutthe on course position.

Ying angle due to wind or other factors.

In the collision course steering function as expressed in Equation 1,supra, the rate of change of heading term dag dt is important from thestandpoint of both stiffness of control and stability. If this term isomitted from the steering function, correction of the course will resultin reduction of the magnitude of the term v dl t Y Consequently, thestiffness of control is limited and may not be of sufficientmagnitude'to provide accurate steering. Specifically, for the conditionunder consideration, the limitation on stiffness of control is to amaximum angular rate of course correction equal to the rate of change oftrue target bearing. Y

However, if this term, i. e.,

dt is included in the steering function, the correction of the course ofthe body being steered results in changes of both terms of the steeringfunction in somewhat compensatory manner. For example, if the body isoil:` course in such position that is positive, a correction of thecourse will reduce this term. However, such'correction will change theterm dHH d! in such manner as to produce a positive value therefor equalto the reduction in the term dof,

Hence, the course correction rate is substantially unlimited and anydesired stiffness of control can be realized. 1t may be noted, however,that in itself the steering function term l represents an unstablecontrol and this characteristic must i be taken intotaccount in theconstruction of any particular steering system. Thus, utilizing only aportion of this control in the steering system results in increased sta-'bility but also entails some reduction in stiffness of control. Also,inasmuch as the control represented by the terms Y K dt is unstable, asnoted above, it is advantageous that this control be disabled wheneverthe steering system is not under the influence of energy emanating fromthe target,

that is, whenever the control represented by the term `larly when thebomb isat some distance from the target.

Collision course steering, as is apparent from the disc'ussionhereinabove and from .Equation l, provides'vcorfrection I'oridierencesbetweentthe bomb iheading a'rrdthe 4:actual course. Howeverfatfairlylargefdistances fbetween bornb fan-d target,'ratherstringentrequirements are placed `:upon the accuracy ofYtheir-ate `of change :of Lbear'ing iin- :formation :requisite 'ffor:accurate steering. For example, :if the bomb `is to fcommence titsiattack, fi. 1e., @to be steered .in accordance with energy emanatingifrom l-the tar-get, lat Aa distance of'2 -rnilesi'frorn the target,1andltheila't'ter-'has la speed ofthe order 40 miles perhourinthe-"direction:normal '-to the-line offattack, the angular rate o'f "change of targetbearing isbnlyfofithegorderfof `degree per second. '-Of course,as thefdis'tancedecreas'es Itliis reiterati :change `increases and ifor`'relatively small distances the :accuracy requirements -on bearinginformation requisite -for :satisfactory fsteering are considerably lessstringent -thantfor greater distances. Thus, each type of steering, i.e., collision course and homing course, ihaslcertin VAfad- `vantages andvalso 'certainpossiblefdisadvantages from a Vpractical standpoint. A

In -accordance with one 'feature .of this .inventiona steering system isso constructed and arranged Ithat it realizes lfthe advantages fof both.collision fcourser'land homing -course steering without 'involving ftheldisadvan- -tages `of Jthe two,i-whereby increased accuracy fof -bornb.trajectory for given bombmaneuver'ability and '-givenlac- `Jcuracy oftarget Ybearing information iis attained. AMore specifically, inaccordancerwithsonerfeaturefof Ithis' invention, 4both-.collision Vandhoming lcourse steering are fpro- "vided :in ysuch :relation tha't =forlarge :distances between bomb andtarget fthe Jbomb Iis :directedsubstantially valong ia ihomingcourse, :in proximity lto the *target itLis #steered :substantially along :the collision course, and .forinterme- :diate :distances the .steering echanges "automatieally fand:gradually from homing :course fto collisiontcourse the Fbomb approaches=the target :Such fa rsystem, illustrative of -Aone embodiment lof fthisinvention, fis :shown in 'iblock -diagram form "in Fig. land comprises:a :detector 10 `responsive to .energy-'emanating .'from a 'targetyforproducing la "signal proportional "to -tthe relative target bearing,12T, a "differentia'tor 211 energizedin accordance with the output :ofthe v'detector 10 for pro- Yducingra signaliproportional toithe rate o'fchange fofrrelartive target bearing, Y

and `agyroscope.element 1.2 for producing a signal @proportional -to therate r.of :change :of bomb heading,

The three signals lnoted are applied to fancon'trol F13 :for .an.actuator 15 rin :such :manner .that Vthe steering rudder :1.4isdetlected in one tdirec'tionor'the :other in ;acc,or,dance with ithepolarity and amplitude `fof the resultant lo'f athe :three signals. v

The elements ofthe system illustrated Ein Eig. 2,.-'itavill yheunderstood, are mounted appropriately @on a flaombtcfarryinganiexpolsive .charge. The bomb Aitselfmayalie, mechanically,of construction similar to aircraftf'provided with eautomatic pilots.:In-asmuch .as isuch constructions :are kinown, .in the interests @ofsimplicity, fillus'tration :there- .of-has been omittedfromthelrawingg.`

.A specific steering system -.of l`the configuration shown sin fFig. 2andintended -to be :energized :inaaccordance radiant heatremanatingtrema-.target is::illnsnatedn'n 'Eig. T8. IIn this system, .the detector"comprises :a mirror d'6 mounted 'opposite ya parabolic reflector 1l7fat the 'focal rpoint of =which :a bolometer :128 is mounted, fthebolometer 1being highly sensitive l-tor-'infra-red Iradiation receivedthereby, whereby its resistance Ivaries in Vaccordance Withisuchnradiation. 'The ymirror .isA -oscillated at a prescribedtirequencyyforexample zl-'Ocyc'les persecond, as lay a motor "19,Ywhereby lthe' mirror repeatedly scans fa eld. Ef

course, in a bomb steering system the mirror 16 is mount- .ied bom'b :inl:such manner :as sto .scan van angular felrlfahea'dof the bomb.lnhfared `radiationreceived by athe :mirror `16 :is reilected a'to :therreector :17 `and `from y.thellatterrto*.Vthed:olrmleter 18.Thefdirectionofncidenee Vfuponithen'eec'tor 17 iwill ibedependentg'a'sis apparent, .upon zthe :position fof the zmirmr 16.

'lhe bolometer 'includedrinzthe inputscirc'u'it of Tan aamp1ier20itogether with '-a suitable tsource, :such vas :laebattery.21,:and'resistor `22. vThe:ampliierzZtl has-arrelay 23 in 'itsVoutputreirrzuit andiis so biased ,normally'lthat A:the.relayfiscreleased When theel'd :scanned bytthemirror :liisiof Auniform=.temperature .throug'h'out, zthenesistance 'ofAtheflzvolorneterrlsfremainsiconstant. sHowevenifthisield .contains -avvtemperature gdiscor'itinity, :for example, a 're- `gion :of elevated'temperature fd'ue to aan aob'j'ect, :such `Tas a ship, aatrsome',pointzimeachfscannin'g cycle, determined by the position of the objectin the field and, hence, its bearing relative to the bomb, radiantenergy emanating from the object will reach 2the bolometer via themirror 16 and reflector .17. fHence, vthefbolorneter resistanceis`.changed zand r'signal pulses fare :applied to ethe amplifier wherebylthen-clay .23 Eis-.causedtto-operate.

Associated with the mirror 16 is a potentiometer resistor 24 energizedfrom a source, such as a battery 25, the control arm 26 of the resistorbeing coupled to the mirror-hva coupling includingabaclelashintroducingtlinkage indicated at 27. This linkage isconstructed and arranged to establish the same phase relation betweenthesignal obtained from the potentiometer 24, 25 and the .motion ,of the.m.rro1:, :as exists `between the signals re` ceived by `the bolometerand -the .operation -of .therelav Thatis to say, the linkage introducesa lag in potentiometer signal equal to the srn of the electrical delayintroduced by the bolometer and amplier and the delay time Aof .the-relay. Ihus, -cophasic lrelation ris .established .between .thepotentiometersignal .andr'elay operation.

'Ille potentiometer `signal .or voltage, ,it .will hetapparent, is,proportional .to the angle :at .which the fmirror 16 :is receptive ltoradiation. This voltage `is.2 1pplied .to a vcondenser V28 over anbvioustcirciiit incliidinglhearmature 30 and contact '31 of the .relay.'23, `when the relay` flopcrates. Inasmuch as the ,point in ,the`scanning cycle .at which the relay isoperated .as the .result of.reception .of energy by the bolometer .fis Vrelated 'Ito the r position.of 1the mirror corresponding to -that-po'int-.and .the potentiometersignal or voltage .`is ,a function of .the ,position of .the inirronthevoltage to which fheicondenseris charged when "the relay Yoperates isrproportional in magnitude {andre- .lated in polarity to 'the relativetarget bearing, 0T, and hence, represents the'horing course steeringfunction, F.

The`vo'ltage to which 'the condenser 28v is charged 'is Aapplied to `thecontrol `grids-rif the 'amplier devices 29 rana '32. Thus, the outputo'f'thejdevicesz's' proportional to the relative target hearing. "Theoutput of the device '29, which 'also is proportional to the relative'target bearing, `is supplied `to :a condenser 3'3 and resistorSZL boththe condenser 33 and .resistanc'ei'S being small s'o lthat the lvoltagelappearing across the resistor '3'4 isproportional to thetimederivativeofthevltage' to'wliichthe condenser 28 is charged, and, hence,represents the term -n the fcollision course lsteering 'funcfic'snThis'vdltage that is, that appearing across' .the resistor 34, isimpressed upon the input circuit ofthe amplifier device 35 as willappear from the description hereinafter. Y

rlhe relay I-23 is providedwithasecoud armature 'and associated contact'37 @included 'in 'the energizing circuit for a second relay 38,thisfcircuitincludingalso a source, :such :as `a battery 39, aY'resistor -'40 'and a condenser 41 "bridged across the 'resistor 40 andrelay kfwinding'in series. The time yconstant of 4thellresiistance-capacitancecircuit .den'ed by 'the condenser '41, resistor40 and 3relaywilding is made such by correlation of the parametersinvolved that the relay'38 Vremains continuously operated when the relay23 operates momentarily'on each scan, i.v e., when an object, i. e.,target, is present in the field scanned by the mirror 16. The relay 38is provided with a pair of armatures 42 and 43 associated with -contacts44a andr45a and 44b and 45h respectively. The armatures 42'and 43 areconnected respectively to the midpoint of'aV source, such as a battery46', bridged across a potentiometer resistor 47, and the contact arm 484of lthis resistor. The contact arm 48 isdriven by a gyroscope 49 whichvis so mounted on the bomb and so constructed in ways known in the artthat the amplitude of deliection of the contact be disabled when thecontrol corresponding to the term 0T Ti? is absent, i. e., when noenergy from a target is received at the mirror 16. The controlcorresponding tothe term is of a sense opposite to thatl of gyroscopestabilizing control. Thus, the control due to the term noted may bedisabled in effect for the purpose intended by making the sense of thecontrol due to the gyroscope such that this control is applied as astabilizing control when no target energy is received at the mirror.This is accomplished in the system illustratedin Fig. 3, for, as isapparent, when the relay 23 is not operating, the relay 38 is releasedand the signal due to the potentiometer 46, 47 is impressed upon thegrid of the device 35 in the circuit traced from the grid of the device,over contact 45a, armature 42, to the potentiometer 46, 47 and contactarm 48, and thence to the cathode of the device 35 by way of armature43, contact 44h `and resistor 34, whereas when a target appears in thefield scanned, the relay 38 operates as noted heretofore and the signaldue to the gyroscope and associated potentiometer is then applied to thegrid circuit of the device 35 closed over armature 42 and contact 44aand over armature 43 and contact 45b. That is, operation of the relay 38effects a reversal in polarity of the signal due to the gyroscopecontrol, as applied to the grid circuit of the device 35.

When the relay 38 is operated, the voltage applied to the grid circuitof the device 35 is proportional to the sum @f dt represented by thevoltage across the resistor 34, and @E dt represented by the voltage dueto the potentiometer 46, 47. Thus, the output of the device 35represents the collision course steering function.

The anodes of the devices 32 and 35 are connected directlyto one anotherand to the anodes of other devices described hereinafter, and in circuitwith a control relay Y50 andnsnource 51. The relay comprises a pair ofcontacts 52 and an armature 53 which may be biased, as by a v arm and,hence, the signal obtained from the.pote'ntiom-v ,spring 5,4, so thatnormally it is out of engagement with both the contacts 52. The relay 50serves to control the direction of rotation of a reversible motor 15having a pair `tiffield windings 55 the energizing circuit of whichincludes the source 56, armature 53 and a respective contact 52. ThefieldV winding circuits are such that when the armature53 engages onecontact 52, the motor 15 will revolve in one direction and when' thearmature engages the other contact, the motor will revolve in the otherdirection. rudder 14, which is coupled to the motor by a suitablelinkage indicated by the broken line 57, is

i detlected, accordingly, in one direction or the other. VAs

is apparent, which of the contacts 52 is engaged by the armature 53, andhence the direction of deflection of the rudder 14, is determined by thecurrent supplied to the relay 50. The latter, in turn, is determined bythe resultant of the several controls. Y

One of these controls, provided by way of the device 32, is inaccordance with the homing course function; another, provided by thedevice 35, is in accordance with the collision course function.Neglecting, for the moment, other controls, it will be seen that when atarget is within'the field scanned by the mirror 16, the control signalfor the relay 50 comprises homing course and co1- lision coursecomponents. The relative strengths of the components may be adjusted byresistors 58 included in the cathode circuits for the devices 32 and 35.

As has been pointed out heretofore, for large distances between the bomband the target, homing course steering is desirable whereas for smalldistances collision course steering is desirable. Thus, advantageously,the resistors V58V are made such that for conditions corresponding tosuch large distances, the homing course component of the control signalfor the relay is large in comparison to the collision course component.As the bomb approaches the target, the rate of change of true targetbearing per degree of course error increases rapidly. Thus, thecollision course steering component increases automatically, relative tothe homing'course component, as the bomb approaches the target and, forsmall distances, essentially collision course steering control isrealized.

In some cases, proportional steering may be desirable. This may beobtained by the introduction of another component in the control signalfor the relay 50. In one construction, such component may be provided bya potentiometer including a source 59 and resistor 60 the contact arm 61for which is coupled to the rudder 14. The potentiometer 59, 60 isincluded in the grid circuit of an amplifier device 62 in such mannerthat the output of the device is varied in the sense opposite to that ofthe resultant of the components, due to the devices 32 and 35, resultingin deflection of the elevator. The relative sensitivity of the follow-upcontrol thus provided may be adjusted by a resistor 63 included in thecathode circuit of the device 62. When the signal component due to thepotentiometer 59, 60 is equal to the components due to the steeringcontrols provided by the devices 32 and 35, the rudder 14 remains in theposition requisite to maintain the bomb on-course or oscillates at smallamplitude about this position.

Other control components may be provided by way of of an additionalamplifier device 64, the control grid circuit of which is energized inaccordance with appropriate signals. For example, in a system such asdescribed for steering the bomb horizontally, the input signals for thedevice 64 may be derived from a compass element so that this deviceeffects control of the relay to maintain the bomb upon a preset coursein the absence of a target in the field scanned by the mirror 16. Suchcompass control may be disabled, as by operation of the relay 38, when atarget appears in the eld noted.

Although the invention has been described thus far particularly withreference to steering a bomb in the Vhorizontal direction, it may beembodied also in systems case, of course, the direction of oscillationof the mirror "1'6 =wou`ld lbe -at '-r'ight `angles *to J'the 'directionof scan for 'horizontal steering. ln a cvertical steering system, theadditional controls -provided `-by `way'of` the'device -64 may 1besuch,Vfor example, Aas to maint-ain the l*bomb lat l-a 'pre- `assignedaltitude -in the Vabsence of 'a 'target within the ield viewed or I`for-aprescribed time after launching tof the bomb, lortocontrol Cthe rate'ofclim'b Vor drive'for sim- -iilar conditions. p

It will 1betunderstoo'rl, lo'f course, that Jtwofsystems, loneforvertical and the other-forilrorizontal:steering may be vvutilized,*theetwo Lbeing 4effective to guide the bomb :in vvarious ways dependentlupon the tactical m,procedure 'de- Lsired. For example, *the 'two'systems may ire-so :con- `-'structed and ,arranged that fthe *bomb fismaintained at 'a kprescribed. altitude, by 'a control signal obtainedfromthe device "64 fin the vertical 'steering system, 'and is .steeredhorizontal only A"in accordance with energy from the ltarget receive'dattheniirror "1'6 in'tlreihorizontal system, untilit is Within apreass'ijgn'ed range oftbe target "Wlhere- `upongverti'c'al steering isV'transferred 'from altitude control to control in accordance :withtarget signals and thereupon J4both v)systems guide "the '.bomb toward.the target, for example, along a collision course. 'The transfer, in"the'veriticalsystem, from altitude'totarget signal control may hee'ected 'by agate or transfer element associated with'the ampIiiierZOjand .device `64 and operable 'to Henable 'the ampliiierzto `disable thedevice 6'4 only when the level of signals received by the boilometer '18is of at least a preassigned magnitude.

It will be understood also `that the speciiicernbodirnent of theinvention shoumand ,described is but illustrative and that variousmodications may be made therein without departing from the scope andspirit of this invention as defined in the appended claims.

What is claimed is:

1. A steering system for a moving body, comprising a steering member,means responsive to radiant energy emanating from a target for producinga rst signal related in sense and amplitude to the direction and rate ofchange, respectively, of the bearing of the target relative to the body,means for producing a second signal related in sense and amplitude tothe direction and rate of change, respectively, of heading of saidbody,.means for resolving said first and second signals into a controlsignal related in sense and amplitude to the algebraic sum of said first`and second signals, and means for effecting actuation of said steeringmember controlled in accordance with said control signal.

2. A steering system in accordance with claim l comprising means forreversing the sense of said second signal when the target radiant energyreceived by said detector means is below a preassigned magnitude.

3. A steering system for a moving body, comprising a steering member,control means for effecting dellection of said steering member in onedirection or the other in accordance with the polarity of a controlsignal applied to the control means, means responsive to radiant energyemanating from a target for producing a first signal of polaritydetermined by the direction, and amplitude proportional to the rate ofchange of bearing of the target relative to the body, means forproducing a second signal of polarity determined by the direction, andof amplitude proportional to the rate of change of heading of said body,and means for resolving said rst and second signals into a controlsignal applied to said control means and of polarity and amplitudedetermined by the algebraic sum of said first and second signals.

4. A steering system in accordance with claim 3 comprising meanscontrolled by said radiant energy responsive means for reversing thepolarity of said second signal when no target radiant energy is receivedby said responsive means.

5. A steering system for a moving body, comprising a steering member,detector means responsive to wave energy *emanating from a ltarget,`means controlled 'by said 'detector means for producing ra rst signalurelated a'in 'polarity and amplitude `to the irbearing l'of the 'targetrelativedothe lbody, meansffor producing a second signal related `inpolarity 'and'amplitude 'to the bearing of lsaid target v'with respecteto 'a reference direction, means `4for 'producing a 4control 'signal opolarity and 'amplitude determined by thealgebraicsumofsaidirstand'second signals, and 'means controlled inaccordance with said control signal 'for actuating lsaid lsteeringmember.

6. A steering 'system :for la moving `body, 'comprising r'a nsteeringmen'iber; 'detector means responsive to wave -energy emanatingffromatarget,'means controlled bysaid detector :means or'mproducing a rstsignal vrelated 1in i polarity Aand! Aan'iplitude to the bearing 'of thetarget relative tojthe body, means energized 'in accordance 'with saidiirst1si`gnail ,for -producing a YVsecond 'signal propor- 'tional *tothe time derivative Vof said first signal, 'means for producing .a third'signal jpolarity 4and amplitude determined bytthe'rate of change of`heading of saidbody, 'meanstforresolving said 'second and *third signals'in com- 'hina'tion into a Acontrol signal of polarity andamplitude deterniinedby the algebraic sum of Vsaid second and thirdsignals, and means controlled in accordance with 'said gyemanating froma target, means controlled by sa'id detector means' for producing afirst Asignal related in vpolarity and .amplitudeto the 'bearing 'ofthetargetelative 'to jthe body1`means "energized in accordancelW'ith'said iirst si'gnl "forproducing a second signl'proportionalto thetime derivative of said first signal, means for producing a third signalof polarity and amplitude determined by the rate of change of heading ofsaid body, means for resolving said rst, second and third signals incombination into a control signal of polarity and amplitude determinedby the algebraic sum of said first, second and third signals, and meanscontrolled in accordance with said control signal for actuating saidsteering member.

8. In combination, radiant energy responsive means for repeatedlyscanning an angular eld, means actuated in accordance with the motion ofsaid scanning means for producing a signal of polarity and amplitude atany time determined by the position of said scanning means at that time,a condenser connected in a normally open circuit With said signalproducing means, means for closing said circuit at the time in eachscanning cycle at which radiant energy is received by said responsivemeans from a source in said eld, whereby said condenser is charged to avoltage of polarity and amplitude determined by the bearing of saidsource relative to said responsive means, means energized in accordancewith said voltage for producing a signal substantially proportional tothe time derivative of said voltage, and means energized in accordancewith said signal.

9. In combination, a mirror, means for oscillating said mirror,potentiometer means coupled to said mirror for producing a directcurrent signal of polarity and amplitude determined by the position ofsaid mirror at any instant, a normally open utilization circuitincluding said potentiometer means, and means responsive to wave energyreected from said mirror for closing said circuit whenever said mirrorencounters an energy discontinuity in the field scanned thereby.

10. In combination, a mirror, means for oscillating said mirror,potentiometer means coupled to said mirror for producing a directcurrent signal of polarity and amplitude determined by the position ofsaid mirror at any instant, a condenser having a normally open chargingcircuit including said potentiometer means, means responsive to waveenergy reected from said mirror for closing said `circuit when saidmirror received waver energy from a mined by the bearing of said sourcewith respect to said 1f mirror, means energized proportionately to saidvoltage for producing a signal substantially proportional to the timederivative of said voltage, and means energized in accordance with saidsignal.

11. In combination, a mirror, means for oscillating said mirror,potentiometer means coupled to said mirror for producing a directcurrent signal of polarity and amplitude determined by the position ofsaid mirror at any instant, a condenser having a normally open chargingcircuit including said potentiometer means, means responsive to waveenergy reflected from said mirror for closing said circuit when saidmirror receives wave energy from a source in the field received thereby,whereby said condenser is charged to a voltage'of polarity and amplitudedetermined by the bearing of said source with respect to said mirror, aiirst electron discharge device having an input 4circuit including saidcondenser and having an output circuit including a resistance andcondenser in series and of such relative constants that the potentialacross said resistance is substantially the time derivative of theinputY signal to said device, a second electron discharge device havingan input circuit including said resistance, and

.operating means connected to the output circuit of said second device.12. A steering system for a moving body, comprising a steering member,control means for effecting deection of said steering member inaccordance with the polarity of the energizing signal applied to saidmeans, an ener- Y t 12 Y t gizing circuit for said control means,including a pair of electron discharge devices the output circuits ofwhich are in parallel relation, means responsive to radiant energyemanating from a target for producing a iirstV signal of polarity andamplitude determined by the bearing of said target relative to the body,means for controlling f the output of one of said ydevices in accordancewith said trst signal, means energized in accordance with said outputfor producing a second signal of amplitude determined by the rate ofcharge of said bearing, an input circuit for the other of said devices,means for impressing said second signal upon said input circuit, andmeans for impressing upon said input circuit a third signal of polarityand Vamplitude determined by the direction and rate of changerespectively of the heading of said body.

13. A steering system in accordance with claim 12 comprising means forreversing the polarity of said third signal when the energy received bysaid radiant energy responsive means is of less than a preassignedmagnitude.

14. A steering system in accordance with claim 12 Vwherein said radiantenergy responsive means includes a mirror, means for oscillating saidmirror, means actuated 4in accordance with motion of said mirror forproducing a direct current signal of polarity and amplitude at any timedetermined by the position of said mirror at that time, a condenserconnected in a normally open circuit with said direct current signalproducing means,V and Vmeans Vresponsive to energy reflected from saidmirror for closing said normally open circuit when said mirror re-,ceives energy from the target.

No references cited.

